PROTEIN YEAST ISOLATION AT THE MICROSCALE LEVEL, INCORPORATING 2-D GEL ELECTROPHORESIS, WILL BE A CENTRAL COMPONENT IN THIS RESOURCE CENTER FOR THE STRUCTURE DETERMINATION OF PROTEINS IN YEAST CELLS THAT ARE INVOLVED IN A VARIETY OF BIOLOGICAL PROCESSES, INCLUDING DNA REPAIR, THE CELL CYCLE AND SIGNAL TRANSDUCTION. RATHER THAN A GLOBAL DATA BASE STRATEGY OF EXAMINING 1000 OR MORE PROTEINS FROM A CELL LYSATE, THE APPROACH TO BE TAKEN HERE WILL BE A FOCUS ON PARTICULAR BIOLOGICAL QUESTIONS. THUS, APPROPRIATE ENRICHMENT VIA AFFINITY SELECTION PROCEDURES WILL BE UTILIZED PRIOR TO 2-D GEL OPERATION. AFTER SEPARATION, THE SPOTS WILL BE BLOTTED ON MEMBRANES AND THEN DIGESTED FOR LC/CE/ESI/MS/MS ANALYSIS.